Bitcoin prices have been dropping steadily after news broke that the Securities and Exchange Commission had launched an investigation of cryptocurrency-related tech companies and advisors this week.

At 14:34 UTC today, the price of one bitcoin token traded at $10,811, down 3% from $11,165.66 just 12 hours earlier. While the exact cause of the drop in value isn't clear, market observers believe it's related to the "scores of subpoenas" the SEC had issued to tech companies and advisors linked to the virtual currency market. 

Specifically, the SEC is targeting initial coin offerings (ICO) to investigate how they're structured. ICOs are not heavily regulated, unlike public stock offerings. Cryptocurrency startups raise money by issuing digital tokens through initial coin offerings. 

SEC Chair: 'Every ICO I've Seen Is a Security'

Last month, SEC chair Jay Clayton signaled his agency would crack down on the unregulated cryptocurrency market when he testified before the Senate Banking Committee.

"I believe every ICO I’ve seen is a security," Clayton said. (See more: SEC Chair Testified About Cryptocurrency Regulation Before Senate.)

In December 2017, Clayton warned about the potential for scams in the digital currency space, and said there's a "substantial risk" that victims would not be able to recoup their losses. (See also: SEC Chair Warns Cryptocurrency Investors to Beware.)

"A number of concerns have been raised regarding the cryptocurrency and ICO markets, including that, as they are currently operating, there is substantially less investor protection than in our traditional securities markets, with correspondingly greater opportunities for fraud and manipulation," Clayton warned in a letter. 

Meanwhile, the price of Ethereum – the second most valuable virtual currency by market capitalization – also plunged on the SEC news. At 15:30 UTC, ETH traded at $855.15, down from $876 just 12 hours earlier.

And the market caps of all top 10 virtual currencies sank, with the exception of bitcoin, according to CoinMarketCap.com.  (See also: SEC Halts Trading In 3 Firms Linked To Blockchain and Cryptocurrencies.)

As the SEC expands its probe, the Internal Revenue Services wants to remind Americans that If you made money from bitcoin's skyrocketing prices, you'll probably have to pay taxes on your crypto gains. (See more: The IRS Wants to Tax Your Bitcoin Gains.)

Investing in cryptocurrencies and Initial Coin Offerings ("ICOs") is highly risky and speculative, and this article is not a recommendation by Investopedia or the writer to invest in cryptocurrencies or ICOs. Since each individual's situation is unique, a qualified professional should always be consulted before making any financial decisions. Investopedia makes no representations or warranties as to the accuracy or timeliness of the information contained herein. As of the date this article was written, the author owns no cryptocurrencies